Implement Infermatic AI adapter

[op-simoneromeo]

Summary

• replace the Infermatic stub with a real OpenAI-compatible chat-completions adapter against https://api.totalgpt.ai/v1/chat/completions
• use INFERMATIC_API_KEY, sane default/example models from the Infermatic docs, dry-run short-circuiting, extra parameter passthrough, usage mapping, and provider error excerpts
• add focused mocked fetch coverage for dry-run, request shape, text-choice fallback, and error handling

Validation

• corepack pnpm@9.12.0 exec vitest run packages/ai/infermatic/src/index.test.ts
• corepack pnpm@9.12.0 --filter @profullstack/sh1pt-ai-infermatic typecheck
• corepack pnpm@9.12.0 --filter @profullstack/sh1pt-ai-infermatic build
• git diff --check
• common secret-pattern scan over the changed Infermatic files

No real Infermatic API key or production secret was used; tests mock fetch.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.